Some exerpts:
"The leakage very likely isn’t over, either. The Tokyo Electric Power Company, the operator of the plant, said Sept. 20 that it believed that something on the order of 200 to 500 tons a day of groundwater might still be pouring into the damaged reactor and turbine buildings.
Chernobyl-induced radiation in the Black Sea peaked in 1986 at about 1,000 becquerels per cubic meter, he said in an interview at his office in Woods Hole, Mass. By contrast, the radiation level off the coast near the Fukushima Daiichi plant peaked at more than 100,000 becquerels per cubic meter in early April.
Mr. Buesseler said there were grounds for concern about bioaccumulation of radioactive isotopes in the food chain, particularly in seaweed and some shellfish close to the plants. A fuller understanding of the effect on fish that are commercially harvested will probably take several years of data following several feeding cycles, he said.
But there was also an unpleasant surprise. 'Rather than leveling off toward zero, it remained elevated in late July,' he said, up to about 10,000 becquerel per cubic meter. ‘That suggests the release problem has not been solved yet.'
The working hypothesis is that contaminated sediments and groundwater near the coast are continuing to contaminate the seas, he said." New York Times